<template>
	<div>
		<router-link
		tag="div" 
		to="/"
		class="header-abs"
		>
			<div class="iconfont header-abs-back">&#xe624;</div>
		</router-link>
		<div 
		class="header-fixed"
		v-show="showAbs"
		:style="opacityStyle"
		>
			<router-link to="/">
		        <div class="iconfont header-fixed-back">&#xe624;</div>
		        景点详情
		    </router-link>
		</div>
	</div>
</template>

<script>
export default {
	name: 'DetailHeader',
	data() {
		return {
			showAbs: false,
			opacityStyle: {
				opacity: 0
			}
		}
	},
	methods: {
		handleScroll() {
			const top = document.documentElement.scrollTop
			if(top > 60) {
				let opacity = top / 140
				opacity = opacity > 1 ? 1 : opacity
				this.opacityStyle = { opacity }
				this.showAbs = true
			} else {
				this.showAbs = false
			}
		}
	},
	activated() {
		window.addEventListener('scroll', this.handleScroll)
	},
	deactivated() {
		window.removeEventListener('scroll', this.handleScroll)
	 }
}
</script>

<style lang="stylus" scoped>
@import '~styles/varibles.styl'
.header-abs
    position: absolute
    left: .2rem
    top: .2rem
    width: .8rem
    height: .8rem
    line-height: .8rem
    border-radius: .4rem
    text-align: center
    background: rgba(0, 0, 0, .8)
	.header-abs-back
	    color: #fff
	    font-size: .4rem
.header-fixed
	z-index: 2
	position: fixed
	top: 0
	left: 0
	right: 0
	height: $headerHeight
	line-height: $headerHeight
	text-align: center
	color: #fff 
	background: $bgColor
	font-size: .32rem
	.header-fixed-back
		position: absolute
		top: 0
		left: 0
		width: .64rem
		text-align: center
		font-size: .4rem
		color: #fff
</style>